Drug cartels are taking to the ocean. That's because security along the land border between the U.S. and Mexico has been beefed up. Smuggling off the coast of Southern California is up 30 percent this year, according to the government, and that has the Coast Guard and Homeland Security warning of an increasingly dangerous situation off the busy coast.

NPR's Kirk Siegler reports.

KIRK SIEGLER, BYLINE: Coast Guard Chief Petty Officer Terrell Horne was in command of the cutter Halibut when he got a call in the predawn hours of December 2nd. A suspicious boat without lights was reported near Santa Cruz Island, about 20 miles off the coast of Southern California. When he and his crew loaded into a smaller boat to confront the smugglers, the situation turned tragic.

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SIEGLER: The Coast Guard says Horne is the first law enforcement officer ever to be killed by suspected smugglers in the waters off the California coast. At the somber funeral, he was remembered by hundreds, including Lieutenant Stewart Siebert who was on patrol with him that night.

LIEUTENANT STEWART SIEBERT: He was undeniably the very best kind of chief. He was a big brother and he was a guardian angel to us all.

SIEGLER: The tragedy has focused attention on the sharp rise in smuggling activity off the coast of California.

At the Port of Los Angeles, the Coast Guard is collecting information about two more smuggling incidents just this week, both involving panga boats like the one that rammed Officer Horne. Now these are the vessels of choice for the notorious Sinaloa drug cartel. One of these pangas wasn't just carrying drugs, says Jim Jenkins, the Coast Guard commander here.

CAPTAIN JIM JENKINS: It was an alien smuggling operation and they apprehended the aliens. They apprehended the smugglers who were driving the boat. And they apprehended some folks on shore that were there to drive them away.

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SIEGLER: You can see one of these pangas that the Coast Guard recently seized behind a chain-link fence, where I've stopped along a road here at the Port of Los Angeles. I mean, they look basically like something a tourist might hire in a Mexican resort area, you know, to go snorkeling or fishing. They're really just open air longboats. Some can carry up to a few dozen people, albeit not safely.

CLAUDE ARNOLD: I mean, in this area, it's definitely the new front for us.

SIEGLER: Claude Arnold is the special agent in charge of the L.A. area for Immigration and Customs Enforcement, or ICE. He says pangas are fast, equipped with powerful motors and they're hard to catch.

ARNOLD: And a lot of times if they hear an aircraft flying overhead, that they think may have spotted them, they paint their watercraft the same color as the ocean. They pull a tarp over it and they'll sit for hours.

SIEGLER: As the Coast Guard has caught on to the pangas, smugglers are going further out into the Pacific and further north along the coast. And one of those suspected smuggling operations the Coast Guard intercepted this week happened near Santa Barbara, more than 200 miles north of the border. And as the word has gotten about pangas, authorities believe the smugglers are already starting to switch to pleasure boats that can pull into a marina full of yachts without drawing much attention.

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SIEGLER: Now, all of this presents a real challenge for the Coast Guard and local commander Jim Jenkins. His officers have to monitor the country's busiest port, assist recreational boaters and fishermen, and now safeguard against smuggling.

JENKINS: If we can't control what's coming and going from the country, then we have a significant concern for national security. So that's why our whole team is committed to countering this threat.

SIEGLER: While the Coast Guard has ramped up its patrols in recent months, the agency doesn't yet have a dedicated unit or a counter smuggling operation. But that could change, after it conducts its own internal investigation of the events surrounding the death of Chief Petty Officer Terrell Horne.